The present invention relates to a method of and device for tracing hydraulic fractures, stimulations, cement jobs, etc. in oil and gas wells.
Methods of and devices for tracing hydraulic fractures, stimulations, cement jobs, etc. are known. One of such methods includes injection of radioactive materials into the slurry and later logging with a gamma ray tool. This method has the disadvantage that it can be harmful to personnel and the environment. Some of the known methods are disclosed for example in U.S. Pat. Nos. 4,926,940; 5,044,436; 5,151,658; 5,723,781; 6,003,365. It is believed that the existing methods and devices of this type can be improved.
Accordingly, it is an object of the present invention to provide a method of and a device for tracing hydraulic fractures, stimulations, cement jobs, etc. in oil and gas wells, which avoid the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a method of and device for tracing hydraulic fractures, stimulations, cement jobs, etc. in oil and gas wells, which does not use radioactive materials for tracing the above mentioned structures and therefore is not harmful to personnel and the environment.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of tracing hydraulic fractures, stimulations, selective cement jobs, etc. in oil and gas wells, which includes the steps of introducing into a well in a zone of interest a plurality of radio frequency transmitting elements each having an identification, moving in the well a reader tool operative for transmitting radio waves so as to generate and send a radio frequency signal for activating the radio frequency transmitting element and thereafter to receive a radio frequency signal returned from the corresponding radio frequency transmitting elements together with the identification of each radio frequency transmitting element, and analyzing data related to the sending of the radio frequency signal from the reader tool to the radio frequency transmitting element, and the receiving of the radio frequency signal from the radio frequency transmitting elements with the identification of the radio frequency transmitting elements so as to trace a corresponding hydraulic fracture, stimulation, selective cement job, etc., in the zone of interest.
Another feature of the present invention is a device for tracing hydraulic fractures, stimulations, selective cement jobs, etc. in oil and gas wells, comprising a plurality of radio frequency transmitting elements introducable into a well in a zone of interest and each having an identification; a reader tool movable in the well and operative for transmitting radio waves so as to generate and send a radio frequency signal for activating the radio frequency transmitting elements and thereafter to receive a radio frequency signal returned from the corresponding radio frequency transmitting elements together with the identification of each radio frequency transmitting element; and means for analyzing data related to the sending of the radio frequency signal from the reader tool to the radio frequency transmitting element, and the receiving of the radio frequency signal from the radio frequency transmitting elements with the identification of the radio frequency transmitting elements, so as to trace a corresponding hydraulic fracture, stimulation, selective cement job, etc., in the zone of interest.
When the method is performed and the device is designed in accordance with the present invention, tracing of hydraulic fractures, stimulations, selective cement jobs, etc. can be performed without the use of radioactive materials, and therefore without any harm to personnel and to the environment.